The total amount of bombs dropped by British and American aircraft on targets in southern Iraq has increased dramatically over the past few months, in a clear indication that the no-fly zone is being used to destroy the country's air defence systems in anticipation of an all-out attack.
Ordnance dropped on southern Iraq in response to threats has increased by 300% since March this year, according to figures released by the Ministry of Defence today in response to questions from the Liberal Democrat spokesman on foreign affairs, Menzies Campbell.
The total tonnage of ordnance released over Iraq between March 1 and November 13 this year was 126.4 tonnes. This is an average of nearly 15 tonnes a month - a 60% increase over last year.
For every threat detected in April and May 2002, about one third of a tonne of bombs was dropped on Iraq; between September and November, every threat was met with an average of 1.3 tonnes.
Ordnance weighing 0.3 tonnes was dropped in April, a figure which rose dramatically to more than 54 tonnes in September.
Whitehall officials have admitted privately that the "no-fly" patrols, conducted by RAF and US aircraft from bases in Kuwait, are designed to weaken Iraq's air defence systems and have nothing to do with their stated original purpose of defending the marsh Arabs and the Sh'ia population of southern Iraq.
"The figures require further explanation. It appears that there has been a marked increase in the destructive power of the bombs dropped while the number of recorded threats has remained about the same", Mr Campbell said yesterday.
He added: "The inference is that these operations have little to do with humanitarian purposes but are being carried out to soften up Iraq air defence systems. There must be a risk that escalation of this kind could provoke wider military action at a time when the inspectors still appear to be able to carry out their work."
Washington has said that the Iraqi response to the patrols - for example, by locking radar on to the aircraft, could amount to a "material breach" of the UN resolution mandating the weapons inspectors now in Iraq.
However, the foreign secretary, Jack Straw, has distanced himself from the Bush administration, making it clear that Britain separates the issue of the no-fly zones from the UN inspectors and UN demands for Iraq to rid itself of weapons of mass destruction. The southern no-fly zone patrols are not covered by a UN resolution.
In recent weeks British and US pilots have been aiming at a wider range of targets, including communications systems, covering a larger area. British military sources say they are concerned in particular about Iraq's carbon-fibre communications network linking Baghdad's military command and control centres with the rest of the country.
Last month Britain and America stepped up the hidden air war over Iraq, with RAF fighters based in Saudi Arabia supporting US navy attack aircraft in practice bombing runs on Iraqi targets.
US navy Super Hornets from the aircraft carrier Abraham Lincoln, which is in the Gulf, carried out mock attacks on airfields, control towers, and other military sites.
The New York Times reported American commanders as saying that the aircraft were "acquainting themselves" with targets they may be called on to attack and were being supported by RAF aircraft.
Earlier this week, Iraqi officials said four people had been killed by western warplanes.